Plasma Protein Z Research Articles

Plasma levels and urinary excretion of protein Z in patients with urolithiasis.

Protein Z (PZ) is a γ-carboxyglutamic acid protein present in plasma that is involved in blood coagulation. Detailed analysis of urinary stones from patients with urolithiasis has revealed that PZ is often found in urinary stones composed of calcium oxalate monohydrate. In this study, we compared blood and urinary PZ concentrations between healthy individuals and patients with urolithiasis. Plasma and urine were collected from healthy individuals and patients with urolithiasis who provided informed consent. PZ was detected as a urinary stone matrix protein in some of the patients. PZ was quantified by ELISA, creatinine was measured by the enzymatic method, and the total protein concentration was measured by the Bradford method. The plasma PZ level was 2.54 ± 1.02 μg/mL in healthy individuals and that in urolithiasis patients classified by stone history were from 1.16 ± 0.77 to 3.73 ± 1.09 μg/mL, which was not significantly different. The urinary excretion of PZ (PZ/creatinine) was also not different in patients with urolithiasis and in healthy individuals (from 54.1 ± 40.9 to 95.4 ± 69.4 ng/mg vs. 73.3 ± 36.0 ng/mg). A positive correlation was found between the plasma PZ level and creatinine-corrected urinary PZ concentration (r = 0.46). Both the plasma level and urinary excretion of PZ in urolithiasis patients were not significantly different with normal individuals. PZ detected in urinary stones as a matrix protein is thought to be incorporated into urinary stones regardless of blood and urine levels of PZ.

Expression and diagnostic value of plasma protein Z and protein Z-dependent protease inhibitor in fetal growth restriction.

Investigating the expression levels of plasma protein Z (PZ) and protein Z-dependent protease inhibitor (ZPI) in fetal growth restriction (FGR) and to explore their diagnostic value in FGR. In this study, the number of pregnant women with FGR, healthy pregnant women (Healthy Control, HC), and childbearing-age women without pregnancy (Blank Control, BC) is 79, 79, and 60, respectively; their plasma PZ and ZPI levels in each group are determined by ELISAs. Then, the correlations between these indices and FGR were assessed using Spearman analysis. Moreover, these indices' diagnostic values for FGR are evaluated using the receiver operating characteristics (ROC) curves. The plasma levels of PZ and ZPI are significantly decreased in the HC and FGR groups compared against the BC group (P < 0.001), whilst the levels of PZ and ZPI in the FGR groups are lower than those in the HC group (P < 0.01) notably. PZ plasma concentration has positive relationship with ZPI concentrations in the HC and FGR groups. The combination of PZ and ZPI, with the Area under the Curve (AUC) 0.92 (95% CI = 0.88-0.96), the sensitivity 0.82, and the specificity 0.88, outperforms everyone. Plasma PZ and ZPI are significantly decreased in pregnant women with FGR, which can be used for pregnant women's FGR screening.

Association of Protein Z intronic G79A Polymorphism with susceptibility to deep vein thrombosis in Egyptian patients with Behcet's disease: A preliminary report

Behcet disease (BD) is a multi-systemic inflammatory disorder, which can affect all types of blood vessels. Thrombotic vasculopathy is one of the major causes complicating the clinical course of BD. This study aims to investigate potential associations between G79A polymorphisms of the protein Z (PZ) gene and venous thrombosis as well as other clinical manifestations in Egyptian patients with BD. Sixty patients who satisfied the International Study Group criteria for BD and sixty healthy age and sex- matched control subjects were genotyped for G79A polymorphisms of the PZ gene by restriction fragment length polymorphism PCR. Plasma levels of PZ were estimated using enzyme linked immunosorbent assay kit. Our preliminary data revealed that, compared to the GG genotype, the AA and AG PZ intron F genotypes were significantly associated with BD susceptibility and with reduced plasma PZ levels. The patients were then subgrouped according to Protein Z G79A genotypes to examine the G79A genotype frequencies according to the clinical characteristics, where there was a statistically significant association between AG and AA genotypes frequencies and deep venous thrombosis. In conclusion, our study nominates the minor A allele of the PZ G79A polymorphism as a discriminatory genetic marker for identification of BD patients at high risk for developing thrombotic events. However, large scaled studies are needed to verify these preliminary results.Key words: Behcet's disease; Protein Z; Deep vein thrombosis; intron F G79A polymorphism.

Low Protein Z Level: A Thrombophilic Risk Biomarker for Acute Coronary Syndrome.

Acute coronary syndrome (ACS) encompasses a range of thrombotic coronary artery diseases. Protein Z (PZ)/PZ-dependent protease inhibitor complex is a natural anticoagulant system with a presumptive role for PZ deficiency in the pathogenesis of ACS. We aimed to evaluate plasma PZ level and role as a risk biomarker in Egyptian patients with ACS. Hundred patients with stable ACS and 60 matched controls were enrolled. ACS patients were divided into 3 clinical subgroups (ST-segment elevation myocardial infarction, non-ST-segment elevation myocardial infarction, and unstable angina), and 2 age subgroups (group A ≤ 55years, and group B > 55years). Plasma PZ levels were evaluated using enzyme linked immunosorbent assay. Lower PZ levels were found in ACS patients' group and clinical subgroups compared with controls. PZ levels showed a decrease with increasing age and were lower in females versus males. Lower PZ levels were found in hypertensive ACS patients in both age subgroups. Smokers and patients with family history of ACS in group A had lower PZ levels, while group B revealed lower PZ among diabetic patients. In group A, increased number of ACS conventional risk factors was associated with lower PZ levels. PZ level 3.7μg/mL was the best cut-off value for prediction of ACS. Logistic regression analyses approved PZ as an independent risk biomarker for ACS. PZ levels are reduced in stable ACS and are significantly and independently associated with increased susceptibility for ACS, denoting PZ deficiency as a reliable thrombophilic risk biomarker in Egyptian patients with ACS.

Low plasma protein Z levels are associated with an increased risk for perioperative bleedings.

Protein Z (PZ) deficiency has been implicated both in bleeding diatheses and in thrombophilia. Considering its ambiguous nature and the conflicting clinical data so far, we set out to evaluate the impact of low PZ on perioperative bleeding in patients who underwent surgical (ENT) interventions involving a high risk of bleeding. After exclusion of other coagulation disorders, 154 Patients were stratified into quartiles according to PZ plasma concentrations to evaluate the relation between PZ and bleeding complications. Low PZ levels were associated with increased blood loss (P<.001), increased need for blood transfusions (P<.001), and a higher rate of surgical revisions (P=.009) in a concentration-dependent fashion. Low PZ caused earlier (within 24hours) and repetitive bleedings (P=.005). The number of major bleeding episodes was significantly increased when low PZ was combined with bleeding history (P<.05). Finally, ROC analyses confirmed the predictive value of low PZ for bleeding complications and PZ-thresholds for clinical practice were determined. Low PZ appears to be an underestimated risk factor for perioperative bleeding. Determination of PZ plasma concentrations might be useful in the preoperative workup in patients with a bleeding history, when detailed clotting analyses remain inconclusive.

Evaluation of protein Z plasma level in beta-thalassemia major patients in Ahvaz city in Iran

Thrombotic episodes occurred frequently in beta-thalassemia major (BTM) patients, leading to hypercoagulability of plasma. Protein Z (PZ) is a vitamin-K-dependent anti-coagulation factor that plays a role in the human homeostatic process. The objective of the current study is to investigate the distribution pattern of PZ plasma concentrations between BTM patients and the normal population in Ahvaz city, the center of Khuzestan province, southwest of Iran. Forty confirmed BTM patients and 40 healthy volunteers were evaluated for complete blood count (CBC) indices and PZ plasma levels. CBC samples were measured using an automated cell counter, and PZ was assayed with an immunoassay method. Statistical analysis was conducted using SPSS software. The ROC curve and binary logistic regression estimated the sensitivity, specificity, and Odd’s ratio for PZ measurement. The mean±SD of the PZ plasma level in normal individuals was 1.68±0.63 μg/mL, and in BTM patients, it was 1.10±0.52 μg/mL. This shows a significant reduction of PZ in BTM patients statistically (CI = 0.99; p<0.001). Further, the mean±SD of the PZ plasma levels in BTM patients who received washed red blood cells was not significantly different from that of patients undergoing packed red blood cell therapy (CI = 0.95; p = 0.320). The area under the curve (AUC) for PZ was 0.759 (p = 0.00). The cut-off value = 1.4 μg/mL of the PZ plasma level had at least 70% sensitivity and specificity in BTM patients. Several epidemiologic studies have shown thromboembolism episodes in BTM patients. In the current study, PZ was reduced significantly in BTMs. We noticed that BTMs have lower plasma PZ concentration might be predisposed to BTM.

Low Protein Z levels in patients with plasma cell neoplasms are inversely correlated with IL-6 levels

Patients with multiple myeloma (MM) have an increased thrombotic risk, but pathogenesis remains uncertain. Low levels of Protein Z (PZ), a vitamin K-dependent plasma protein, are associated with venous as well as arterial thrombosis. The purpose of this study was to analyze PZ levels in patients with plasma cell neoplasms. Patients and methodsThe study consisted of 64 plasma cells neoplasm patients and 42 healthy individuals. Clinical investigations included measurement of plasma PZ and IL-6 levels. ResultsPZ levels in patients with plasma cell neoplasms were significantly lower compared to healthy controls in the entire cohort (1392±659 vs.2010±603ng/mL, P<0.01), as well as in specific disease subgroups; symptomatic MM (1428±652ng/mL, p<0.01), smoldering MM (1437±883ng/mL, p=0.045) and monoclonal gammopathy of undetermined significance (MGUS) (1247±593ng/mL, p=0.01). PZ was negatively correlated with IL-6 levels in MM patients (r=−0.7, P<0.01). There was no significant difference in PZ levels between patients with or without thrombotic event. ConclusionPlasma cell neoplasm patients have low levels of PZ. This is presumably related to the increased IL-6 production by the bone marrow microenvironment, and could have a potential role in the increased thrombotic tendency in those patients.

Circulating protein Z concentration, PROZ variants, and unexplained cerebral infarction in young and middle-aged adults.

Protein Z (PZ) is a vitamin K-dependent plasma protein that exhibits both pro- and anticoagulant properties. Both low and high PZ levels have been linked to ischaemic stroke. Although PZ-lowering gene variants have been found to be less common in ischaemic stroke, the relationship remains unclear. We investigated PZ levels and PROZ variants in a multi-ethnic case-control study of unexplained stroke in participants aged 18 to 64. Plasma PZ was measured in cases (≥2 months post-stroke) and controls. PZ polymorphisms G79A (rs3024735) and A13G (2273971) were genotyped. A combined genetic score (0-4 minor alleles) was created assuming additive effects. A total of 715 individuals (1:1.4 cases:controls) was included. Analyses revealed evidence of a non-linear association. After adjusting for demographic and clinical covariates, PZ levels >2.5 µg/ml (90th %ile) were significantly associated with cryptogenic stroke (OR 2.41 [95 % CI 1.34, 4.34]) as compared with lower levels. Higher genetic score was related to progressively lower levels of PZ, and the presence of four minor alleles was associated with lower odds of stroke (adjusted OR 0.26 [95 % CI 0.07, 0.96]) versus 0 minor alleles. In this multi-ethnic study of young and middle-aged adults, there was evidence of a non-linear positive association between PZ level and unexplained stroke, with a directionally consistent association for genetic variants related to PZ levels and cryptogenic stroke. These findings support elevated PZ levels as a risk factor for cryptogenic stroke.

The possible relationship between epistaxis and protein Z plasma levels

Epistaxis represents a very common emergency in any ear, nose, and throat (ENT) department around the world. Frequently seen in the systemic vascular patients, nasal anatomy the lack of vessels muscular structure, the absence of vasoconstriction ability, the clot formed in the bleeding area further increases the amount of bleeding supports the importance of vascular causes in the etiology. The purpose of our research is to evaluate the relationship between epistaxis and plasma protein Z levels. 18 patients with epistaxis and 30 healthy subjects were investigated. 8 of patients gruop (44.4%) participating the research were women, 10 of them (55.6%) were men, in total 18 people. Control group consisted of 16 women (53.3%), 14 men (46.7%), 30 people in total. Both groups were measured about protein C (PC), protein S (PS), and protein Z (PZ). PC and PS concentrations were determined in plasma by using cholorimetric and the formation clotting methods, respectively. Sandwich enzyme immunoassay method was used for the determination of PZ plasma concentrations. While statistically there were no significant differences detected comparing Protein S and Protein C levels data of control group, (p=0.27 ve p=0.29 respectively). Protein Z levels of patient group was found significantly lower than Protein Z levels of control group and this was found to be statistically significant (p

Low protein Z plasma level is a risk factor for acute myocardial infarction in coronary atherosclerosis disease patients

ObjectivesTo examine plasma protein Z (PZ) levels in acute myocardial infarction (AMI) and chronic coronary atherosclerosis disease (CCAD) patients without history of AMI and explore its potential clinical significance. MethodsPlasma PZ concentrations were measured in 90 AMI patients (Group A), 87 CCAD patients without AMI history who remained free of major clinical events at least one year (Group B), and 88 clinically healthy controls (Group C). ResultsPZ was found to be significantly lower (P<0.001) in Group A (1508.5±486.2ng/mL) compared with Group B (1823.0±607.8ng/mL) and C (2001.7±733.0ng/mL) and in Group A+B compared with Group C (Group A+B 1663.1±570.0 ng/mL, P<0.001). No statistically significant difference was reached between Group B and C (P=0.081). PZ level was significantly correlated with concentration of creatine kinase MB, high sensitive-cardiac troponin T, high sensitive C reactive protein, D-dimer and coagulation factor II and may be a useful predictor for AMI (OR: 1.38, 95% CI: 1.13–1.77, P=0.03). Subgroup analysis showed PZ concentration below the lowest tertile (<1398ng/mL) had a significantly increased risk for AMI and CCAD (OR: 3.39; 95% CI: 1.12–10.31; P=0.03 and OR: 7.39; 95% CI: 2.62–20.79; P<0.001 respectively). ConclusionsPZ deficiency is found in AMI patients and could potentially reflect the myocardium injury, local coagulation activation and inflammation response during the acute phase of coronary atherosclerosis disease.

Influence of protein Z plasma level on thrombin generation assay

Introduction: Protein Z (PZ) is a vitamin K-dependent factor, involved as a cofactor of PZ-dependent protease inhibitor (ZPI) that inhibits the activated factor X on phospholipid surface. A severe PZ deficiency could be associated with ischemic arterial diseases. The aim of this study was to evaluate the influence of PZ plasma levels on thrombin generation (TG) and to detect a hypercoagulable state in patients with PZ deficiency.Patients and Methods: Young patients with personal history of arterial thrombosis and PZ deficiency were included. PZ concentrations were assessed using ELISA method. TG assay was performed using PPP containing 5 pM or 1 pM tissue factor and 4 μM phospholipids with and without thrombomodulin. Then, we focussed on the influence of successive overloads with purified PZ in two patients with PZ deficiency (Pat1PZdef and Pat2PZdef) and industrial PZ deficiency (IndPZdef).Results: First, in 13 patients with PZ deficiency, none influence of PZ level was reported on TG assay parameters. Second, TG profiles performed on Pat1PZdef, Pat2PZdef and IndPZdef were close to the reference TG profile. In presence of TM, there was no difference in TG parameters according to PZ plasma levels. After each overload, real PZ plasma levels were underestimated; differences in standards of purified PZ between the two manufacturers might explain such results.Conclusion: The absence of influence of PZ concentration on TG assay is reliable to the absence of well-demonstrated clinical consequences of PZ deficiency in arterial thrombosis. Clinical consequences of protein Z deficiency warranted further studies.

Plasma Protein Z Levels in Healthy and High-Risk Newborn Infants

Objectives: To evaluate plasma protein Z (PZ) levels in healthy and high-risk newborn infants. Background: Protein Z (PZ) is a vitamin K-dependent plasma protein , As is the case with other coagulation proteins and inhibitors, protein Z is consumed during disseminated intravascular coagulation (DIC), Functionally protein Z has been shown to be a direct requirement for the binding of thrombin to endothelial phospholipids , Protein Z also serves as a cofactor for the inhibition of coagulation factor Xa by a plasma serein called protein Z-dependent protease inhibitor (ZPI), The inhibitory function is exerted by the Protein Z- dependent protease inhibitor (ZPI), which circulates in the human plasma in a complex with PZ , The physiological function of protein Z is still rather ill-defined and may play role in high risk newborn. Methods: This study was conducted on 85 newborns divided in 4 groups ,(group I newborns affected by respiratory distress syndrome (RDS) , group II newborns from mothers with pre-eclampsia, group III newborns small for gestational age (SGA) and group IV healthy term and preterm newborns normal for gestational age. Newborns with sepsis, congenital malformation or hemorrhagic disorders were excluded, Plasma PZ levels was measured. Results: In the neonates of the study groups, protein z level was significant lower in patient group than control group, in group I ( 0.79 ±0.32), group II (0.70± 0.30), group III (0.78 ±0.32) and group IV (1.44 ±0.43) (p value<0.001). Conclusion: PZ deficiency occurs in newborns affected by severe RDS, in newborns from preeclampsic mothers and in SGA newborns, probably owing to activated coagulation in the first two conditions and to reduced PZ synthesis in the last one.

Protein Z, an anticoagulant protein with expanding role in reproductive biology

Protein Z (PZ) is a vitamin K-dependent factor characterized by its homology to other vitamin K-dependent factors (factors VII, IX, and X, protein C and protein S), but lacks any enzymatic activity. Instead, PZ acts as a cofactor for the inhibition of factor Xa through the serpin PZ-dependent protease inhibitor (ZPI). PZ deficiency is associated with a procoagulant state, highlighted by excessive FXa secretion and thrombin production, and is linked with several thrombotic disorders, including arterial vascular and venous thromboembolic diseases. A role for the PZ-ZPI complex in the regulation of physiological pregnancy has been demonstrated, highlighted by the progressive elevation in PZ levels in the first trimester of gestation, which then steadily decline toward delivery. An association between altered plasma PZ concentrations and adverse pregnancy outcomes (recurrent miscarriage, stillbirth, preeclampsia, intrauterine growth restriction, and placental abruption) has been reported. The mechanism by which PZ deficiency leads to adverse pregnancy outcomes is not clear, but it is multifactorial. It may be attributed to the anti-PZ IgG and IgM autoantibodies, which apparently act independently of classical antiphospholipid antibodies (lupus anticoagulant, anticardiolipin, and anti-β2-glycoprotein I antibodies). PZ deficiency has also been reported to be constitutional, and a number of variants in the PROZ (PZ) gene and SERPINA10 (ZPI) gene are linked with specific adverse pregnancy complications. This review summarizes the relationship between adverse pregnancy outcomes and acquired and constitutional PZ-ZPI deficiency, in order to understand whether or not PZ deficiency could be considered as a risk factor for poor pregnancy outcomes.

Protéine Z, polymorphismes du gène de la protéine Z et thromboses

Protein Z (PZ) is a vitamin K dependent protein acting as the cofactor of the protein Z dependent inhibitor (ZPI), in the inhibition of activated factor X bound on the phospholipids. Normal plasma protein Z concentrations have wide variations among individuals, partly explained by a genetic control. Several protein Z gene polymorphisms influence plasma concentration, separately and in combination. The role of PZ in blood coagulation regulation has been demonstrated in vitro. The responsibility of low PZ level in the occurrence of thrombosis has been questioned. However, the roles of PZ plasma level and PZ gene polymorphisms remain debated with conflicting results in arterial, venous, or placental thrombosis. These discrepancies can be explained by the heterogeneity of populations chosen as control, by the PZ interindividual variability, by the small size of the cohorts in mainly retrospective studies and perhaps by the lack of real important influence of this protein on coagulation. PZ measurement is not actually considered as a biological marker of thrombophilia. Large prospective studies remain to be done to investigate its possible role in thrombosis.

Maternal anti-protein Z antibodies in pregnancies complicated by pre-eclampsia, SGA and fetal death

Objective. Low maternal plasma protein Z (PZ) concentrations were reported in patients with pre-eclampsia (PE), a small for gestational age (SGA) neonate, and a fetal demise (FD). Anti-protein Z antibodies (APZ-AB) have been proposed as a possible underlying mechanism leading to low plasma PZ concentrations. The objective of this study was to determine the maternal plasma concentration of APZ-AB in women with a normal pregnancy, and patients with PE, an SGA neonate or a FD.Study design. A cross-sectional study included women in the following groups: (1) non-pregnant women (n = 45); and pregnant women with: (2) normal pregnancies (n = 70); (3) PE (n = 123); (4) SGA neonates (n = 51); and (5) a FD (n = 51). Plasma concentrations of anti-protein Z IgM and IgG antibodies were measured by ELISA. Elevated APZ-AB was defined as >75th, 90th and 95th percentile of the normal pregnancy group. Non-parametric statistics were used for analyses.Results. (1) Patients with an SGA neonate had a higher median maternal plasma IgG APZ-AB concentration than women with normal pregnancies (p < 0.001), and patients with PE (p < 0.001) or with a FD (p = 0.001). (2) The proportion of patients with a maternal plasma IgM APZ-AB concentration >90th percentile was higher in the SGA group than in the PE group (p = 0.01). (3) Patients with PE maternal plasma IgM APZ-AB concentration >90th percentile had a higher rate of villous thrombosis (p = 0.03) and persistent muscularisation of basal plate arteries (p = 0.01) than those with IgM APZ-AB concentration <90th percentile; and (5) Patients with FD and maternal plasma IgM APZ-AB concentration >90th percentile had a higher rate of umbilical phlebitis and arteritis than those with IgM APZ-AB concentration <90th percentile (p = 0.003).Conclusions. (1) Patients with SGA neonates have a higher median plasma concentration of IgG APZ-AB than normal pregnant women, or patients with PE or FD; and (2) maternal plasma IgM APZ-AB concentration >90th percentile was associated with vascular placental lesions in patients with PE, but not in those with an SGA neonate, suggesting that in a subset of patients, these antibodies can be associated with abnormal placentation and pregnancy complications.

Low protein Z levels, but not the intron F G79A polymorphism, are associated with unexplained pregnancy loss

Introduction The present case-control study was designed in order to investigate the association between plasma protein Z (PZ) levels, the intron F G79A polymorphism and unexplained pregnancy loss. Materials and Methods 51 women with at least two consecutive or three non-consecutive fetal losses between the 8th and 12th week of gestation and 47 apparently healthy parous women of reproductive age with no history of pregnancy loss (controls) were enrolled. Allele frequencies of the PZ intron F G79A polymorphism and PZ levels were measured. Results PZ levels (mg/L) were significantly lower in cases (mean±S.D. 1.28 ± 0.56) than controls (1.97 ± 0.76, p < 0.001) and in carriers of the A allele (1.46 ± 0.62), compared to GG homozygous subjects (1.72 ± 0.81, p = 0.044). A higher proportion of cases (41.2%) were PZ-deficient (< 1 mg/L), compared to controls (10.6%, p = 0.001). No significant difference in the frequency of at least one A allele carriers was observed between cases (39.2%) and controls (40.4%). Conclusion(s) It is possible that low PZ levels are a novel risk factor for unexplained recurrent miscarriage or fetal death. The presence of the F 79A allele is associated with significantly lower PZ levels, but, in the present study, was unrelated to unexplained early pregnancy loss.

The G79A polymorphism of protein Z gene is an independent risk factor for cerebral venous thrombosis

Protein Z (PZ), a vitamin Kdependent protein, plays a role in inhibiting coagulation. Its plasma level or PZ gene polymorphisms have been discussed as risk factors for stroke with conflicting results reported between various studies. Only one of these polymorphisms was studied in a cohort of patients suffering from cerebral venous thrombosis (CVT). We performed a retrospective genetic study comparing 100 healthy controls to 54 patients referred to our hemostasis unit after CVT occurrence. We compared the distribution of three PZ gene polymorphisms that may influence PZ plasma levels: A-13G in the promoter and G79A in intron F were tested using previously described techniques, and we developed a technique to evaluate the G-103A in intron A. The G79A polymorphism was significantly more frequent in patients than in controls (p = 0.012): the presence of at least one A allele led to an odds ratio of 2.57 with a 95 % confidence interval of 1.23-5.34. The A-13G polymorphism also showed a nonsignificant trend towards a higher prevalence in patients. The G79A polymorphism of the PZ gene was shown to be a new independent risk factor for cerebral venous thrombosis. Nevertheless, these results have to be confirmed by a prospective study including plasma PZ evaluation.

Plasma Protein Z and Protein C Inhibitors and Their Role in Hypercoagulability of Thalassemia

A hypercoagulable state has been described in thalassemia patients, partly due to a deficiency of inhibitors, protein C (PC) in particular. Since a potential role of a new hemostatic factor named protein Z (PZ) has been reported in hypercoagulability, we evaluated plasma PZ and PC levels in thalassemia and their possible relation to the hypercoagulable state. Sixty subjects with thalassemia major and 10 with thalassemia intermedia (TI) followed at our Department were enrolled in the study. An age-matched control group of healthy subjects was considered. PZ, thrombin-antithrombin complexes, PC concentration (PC:Ag) and activity (PC:Act) were measured. PZ, PC:Ag and PC:Act were significantly lower in thalassemia major and thalassemia intermedia subjects than in 30 healthy controls (p < 0.001), while thrombin-antithrombin complex levels were significantly increased (p < 0.001) and related to PC levels but not to PZ levels (p < 0.05). PZ and PC levels are reduced in thalassemia but only PC has an effect on the thalassemia hypercoagulable state.

Regulation of human protein Z gene expression by liver-enriched transcription factor HNF-4alpha and ubiquitous factor Sp1.

Protein Z (PZ), which regulates blood coagulation, is mainly synthesized in the liver. Its plasma level varies widely among individuals, and is highly sensitive to Warfarin. The mechanism for the basic transcription of the human PZ gene, however, has not been reported. The aim of this study was to elucidate the mechanism of gene regulation for PZ by characterizing its 5'-flanking region. A reporter gene assay using the human hepatoma cell line, HepG2, identified a minimal promoter region (site A) and two enhancer regions (sites B and C) in the PZ gene. DNase I footprinting and electromobility shift assays revealed binding of the liver-enriched transcriptional factor hepatocyte nuclear factor (HNF)-4alpha to site A, the ubiquitous transcriptional factor Sp1 to sites A and C, and an unidentified factor to site B. The co-transfection of an HNF-4alpha expression vector with reporter gene constructs to the non-hepatic cell line HeLa resulted in a significant increase of PZ promoter activity. HNF-4alpha plays a crucial role in human PZ gene expression in hepatocytic cells, and Sp1 is also important. These findings provide the first step toward understanding the mechanisms of the varying plasma PZ levels in individuals under physiological and pathological conditions.

Protein Z and natural anticoagulants in children on peritoneal dialysis and hemodialysis

Hemostatic alterations due to abnormalities in the coagulation and fibrinolytic system may occur in dialysis patients. Protein Z (PZ) is a vitamin K-dependent coagulation protein promoting assembly of thrombin with phospholipid vesicles. The aim of this study was to investigate PZ and natural anticoagulants in children on hemodialysis (HD) and peritoneal dialysis (PD). Protein Z, protein C (PC), protein S (PS), antithrombin III (AT III), and fibrinogen levels were studied in 24 PD, 13 HD patients and 23 controls. Plasma PZ levels in patients on HD were significantly higher than those on PD and control group (p = 0.04, p = 0.03). We observed elevated PC, PS and AT III activities in children on PD when compared to controls (p = 0.011, p = 0.003, p < 0.001). In HD patients, only PS activity was increased compared to controls (p = 0.016). PC and PS activities did not differ between PD and HD patients whereas AT III activity was higher in PD patients compared to HD patients (p < 0.001). Normal/high levels of PC, PS and AT III suggest that children on PD or HD treatment do not seem to have an increased risk of thrombogenesis due to reduction of these proteins. Increased PZ levels, however, might contribute to the hemostatic alterations in children on HD treatment along with other well known abnormalities.